Prevalence and Dynamics of PathogenicYersinia enterocolitica4/O:3 Among Finnish Piglets, Fattening Pigs, and Sows

Abstract

Pigs are considered the main reservoir of Yersinia enterocolitica, hence understanding the ecology of this foodborne pathogen at the farm level is crucial. We calculated Bayesian estimates for the ability of a commercial ELISA diagnostic test kit to detect antibodies against pathogenic Yersinia in pigs. The sensitivity and specificity of the test were 75.4% and 98.1%, respectively. We also studied the dynamics of Y. enterocolitica infection in three farrow-to-finish pig farms by following the same 30 pens of pigs through their lifetime from farrowing unit to slaughterhouse. Each farm was sampled four times, and 864 fecal and 730 serum samples were collected altogether. Pathogenic Y. enterocolitica 4/O:3 was isolated from 31.6% of the fecal samples by culturing, and Yersinia antibodies were detected in 38.2% of the serum samples with the commercial ELISA test. The pathogen was not isolated from farrowing units or all-in/all-out weaning units. However, in the weaning and fattening units using continuous management systems, the pathogen was isolated from every pen at some point of the study. After the pigs were transported into slaughterhouse, 150 tonsils were collected and 96.7% were positive by culturing. Among the strains isolated from feces and tonsils, 56 different genotypes of pathogenic Y. enterocolitica 4/O:3 were found by multiple-locus variable-number tandem repeat analysis (MLVA). Finally, we collected tonsils of 266 sows from 115 farrowing farms, and Y. enterocolitica 4/O:3 was detected in 6.0% of the samples by the culture method, while 77.1% of the tonsils were serologically positive; the estimate for true seroprevalence was 95.8%. In conclusion, sows may not be the main source of Y. enterocolitica for piglets, although sows may still play a role in maintaining Y. enterocolitica in pig farms. Instead, pigs appear to get this foodborne pathogen mainly during the fattening period, especially if continuous management is applied.

Prevalence and Persistence of Multidrug-Resistant Yersinia enterocolitica 4/O:3 in Tonsils of Slaughter Pigs from Different Housing Systems in Croatia

“…The pathogenic bioserotype 4/O:3 is also the prevalent type among Y. enterocolitica isolates from fattening pigs sampled at the slaughter line (tonsils) in other European countries, such as Germany (99% of isolates, 2001, [58]), Switzerland (96% of isolates, 2007, [24]), or Finland, 2000, (100%, [3]). The persistence of this bioserotype of Y. enterocolitica has been confirmed in similar studies in later years in the same countries [36,59], which is in agreement with our results. In contrast, Bonardi et al [40,60] reported lower prevalences (15% and 27%) of Y. enterocolitica 4/O:3 in two surveys conducted in Italy (2014,2016).…”

“…At the other extreme are the studies that found low prevalence: 2%, 4%, 8%, 9%, 11%, and 13% [28][29][30][31][32][33]. Several other studies conducted in Europe in recent years also show very different results and the prevalence of Y. enterocolitica ranges from 3% [34] (Sardinia), to 14% [35] (Central Italy), to 97% [36] (Finland).…”

Genetic Diversity and Distribution of Virulence-Associated Genes in Y. enterocolitica and Y. enterocolitica-Like Isolates from Humans and Animals in Poland

“…The presented study showed the clustering tendency among PFGE and VNTR profiles related to pig origin, 4/O:3 bioserotype and virulence profile and the similarity of PFGE and VNTR profiles between human and pig strains. Genetic and virulotype similarity between human and pig strains determined in this work strongly correlate with recognition fattening pigs and their meats as a main risk factor for transmission of Y. enterocolitica [55]. The same was shown in the studies conducted in Finland and Germany, which proved the genetic relationship of 81% and 83% of tested clinical strains with pig isolates in Finland and Germany, respectively [56,57].…”

Controlled Experimental Infection in Pigs with a Strain of Yersinia enterocolitica Harboring Genetic Markers for Human Pathogenicity: Colonization and Stability

“…Despite some geographic variation, BT4 (mostly comprising serotype O:3 strains) is also the biotype most frequently isolated from pigs and may represent 65% to 100% of the biotypes isolated from this species. BT3 and BT2 are also found on pig tonsils and in feces at slaughterhouses, but in general less frequently ( 5 – 9 ). Pigs are therefore considered the main reservoir of human-pathogenic strains.…”